'Storing solar power underground' - what if it's in a pressurized and compressed form that's easily transported and has a high mass to energy ratio? Brilliant!
(But your information on methane is interesting. I somehow didn't realize it was the biggest component in natural gas; I guess I had assumed it was a more complex hydrocarbon and not considered it further.)
For all the hate that hydrocarbons get they are probably the main reason most of us aren't still living a very primitive existence.
It's like half a joke..